Auditory and Articulatory Systems Lecture Flashcards

Comprehensive vocabulary flashcards covering the anatomy and physiology of the human auditory and articulatory systems.

Audition vs. Speech Overlaid Function

A biological distinction stating that speech is an overlaid function (breathing and eating take primary physiological precedence), whereas hearing is not an overlaid function.

Energy Transducer (Auditory System)

The ear's primary physiological role, converting acoustic energy (outer ear) to mechanical energy (middle ear), hydraulic energy (inner ear), and electrochemical energy (nerve impulses).

Human Hearing Ability Range

The normal human capacity spanning a frequency range of approximately $20 - 20,000\,\text{Hz}$ ($10$ octaves) and a loudness range from the threshold of hearing ($0\,\text{dB}$) to the threshold of pain (approximately $120\,\text{dB} = 10^{12}$).

Four Processing Stages of the Ear

The sequential functional auditory stages: outer ear (collect and amplify sound, aid in localization), middle ear (impedance matching), cochlea (frequency and intensity analysis), and auditory pathway (complex signal processing).

Pinna (Auricle)

The cartilaginous structure of the outer ear lying outside the skull that contributes to sound collection and binaural localization; it attaches to the zygomatic arch and mastoid process of the temporal bone.

Concha Cava

The deep cavity of the pinna forming the entrance to the external auditory meatus.

Helix

The rim-like outer folded margin of the pinna.

Tragus

The cartilaginous flap of the outer ear that partly occludes the external auditory meatus.

Lobule

The soft, inferior portion of the pinna (ear lobe).

External Auditory Meatus (EAM)

An ear canal approximately $3\,\text{cm}$ long and $6\,\text{mm}$ wide that conducts sound from the pinna to the tympanic membrane; its lateral $1/3$ is cartilaginous, lined with cilia and ceruminous glands, and its medial $2/3$ is bony.

Cerumen

Earwax secreted by the epidermis lining the ear canal that protects it from drying out and prevents intrusion of insects and foreign material.

Cilia (Ear Canal)

Fine hair-like projections in the outer ear canal that protect the ear by propelling cerumen and foreign particles outward.

Acoustic Resonance of the EAM

The resonance of the ear canal tube that boosts sound pressure by $15 - 16\,\text{dB}$ between $1.5\,\text{kHz}$ and $8\,\text{kHz}$, matching the primary speech frequency range.

Tympanic Membrane

An oval-shaped, semi-transparent, compliant three-layered sheet separating the outer and middle ear that vibrates in response to sound waves, transducing acoustic energy into mechanical energy.

Umbo

The depressed, thinnest central point of the tympanic membrane where the handle (manubrium) of the malleus attaches internally.

Pars Flaccida

The small, loose, triangular uppermost portion of the tympanic membrane that helps equalize air pressure between the external auditory meatus and middle ear.

Pars Tensa

The larger, taut remainder of the tympanic membrane held tense across the ear canal opening.

Otoscope

A medical instrument equipped with a magnifying lens and light used to examine the ear canal and tympanic membrane by pulling the pinna up and back.

Cone of Light

The characteristic triangular light reflection seen beneath the umbo during otoscopic evaluation when the tympanic membrane is appropriately shaped and positioned.

Middle Ear (Tympanic Cavity)

An air-filled cavity ventilated and drained by the Eustachian tube, housing the ossicular chain, oval and round windows, and middle ear muscles.

Eustachian Tube

A tube approximately $35\,\text{mm}$ long coursing downward and medially from the middle ear to the nasopharynx; it equalizes air pressure across the tympanic membrane and drains mucous secretions.

Pediatric Eustachian Tube Differences

Anatomical variation in children where the Eustachian tube is half as long and positioned more horizontally compared to adults, leading to increased risk of ear infections.

Ossicles

The three smallest bones in the human body—malleus (hammer), incus (anvil), and stapes (stirrup)—that form a mechanical chain transmitting vibrations from the tympanic membrane to the inner ear.

Malleus

The most lateral ossicle whose manubrium attaches to the tympanic membrane and whose head articulates with the body of the incus.

Incus

The intermediate ossicle consisting of a corpus that articulates with the malleus, a short process, and a long process jointed to the head of the stapes.

Stapes

The innermost stirrup-shaped ossicle whose head joints to the incus, crura project inward, and footplate attaches into the oval window via the annular ligament.

Stapedius Muscle

The smallest muscle of the body, which runs from the temporal bone to the stapes; it pulls the stapes posteriorly to reduce excursion amplitude and lower oval window pressure.

Tensor Tympani Muscle

A middle ear muscle running parallel to the Eustachian tube from the tensor veli palatini to the manubrium of the malleus, pulling it medially to tense the tympanic membrane and protect against loud, low-frequency sounds.

Acoustic (Stapedial) Reflex

A reflexive contraction of the middle ear muscles triggered by sounds $80\,\text{dB}$ or more above hearing threshold; after a $10\,\text{msec}$ delay, it reduces sound transmission by $10 - 30\,\text{dB}$.

Impedance Matching (Middle Ear)

The mechanical process that overcomes the $30\,\text{dB}$ loss that occurs when sound transitions from air to cochlear fluid by providing a total gain of $31\,\text{dB}$ via ossicular lever action ($2\,\text{dB}$), surface area ratio of TM to stapes footplate ($25\,\text{dB}$), and membrane buckling ($4 - 6\,\text{dB}$).

Tympanometry

A diagnostic procedure measuring the mobility and compliance of the tympanic membrane in response to sound waves under varying air pressures established in the external auditory meatus.

Bony Labyrinth

The rigid outer protective cavity in the temporal bone consisting of three parts: the vestibule (entrance), semicircular canals (balance), and cochlea (hearing).

Oval Window

The membrane-covered opening in the temporal bone connecting the stapes footplate of the middle ear directly to the scala vestibuli of the cochlea.

Round Window

The membrane-covered opening connecting the middle ear cavity to the scala tympani of the cochlea, which vibrates in response to fluid movements.

Cochlea

A fluid-filled, snail-shaped bony structure in the temporal bone coiling $2\frac{3}{4}$ turns from base to apex, serving as the sensory organ of hearing.

Modiolus

The finely perforated central bony core of the cochlea through which nerve fibers of cranial nerve VIII (vestibulocochlear) pass.

Osseous Spiral Lamina

A bony shelf extending outward from the modiolus that incompletely divides the cochlea into the scala vestibuli and scala tympani, anchoring the membranous scala media.

Scala Vestibuli

The perilymph-filled superior duct of the cochlea originating at the oval window and communicating with the scala tympani at the apex.

Scala Tympani

The perilymph-filled inferior duct of the cochlea that terminates at the round window.

Scala Media (Cochlear Duct)

The middle membranous, endolymph-filled division of the cochlea bounded by Reissner's membrane and the basilar membrane, containing the organ of Corti.

Helicotrema

The small communication channel situated at the apex of the cochlea that connects the scala vestibuli and scala tympani.

Basilar Membrane

The floor of the cochlear duct that is narrow and stiff at the base (responding to high frequencies) and wide and flexible at the apex (responding to low frequencies).

Organ of Corti

The sensory hearing structure housed within the scala media, bounded by the tectorial membrane superiorly and the basilar membrane inferiorly, containing sensory hair cells.

Outer Hair Cells

Three rows of sensory receptor cells in the organ of Corti whose stereocilia are embedded in the tectorial membrane, stimulated mechanically by shearing forces during basilar membrane displacement.

Inner Hair Cells

A single row of sensory receptor cells not attached to the tectorial membrane, activated primarily by the fluid turbulence and motion of endolymph at maximum basilar membrane displacement.

Traveling Wave (Basilar Membrane)

The mechanical fluid wave travelling along the basilar membrane from base to apex that peaks at the specific region matching the vibration frequency before quickly damping.

Place Theory of Frequency Discrimination

The auditory theory stating that different frequencies resonate at distinct physical locations along the basilar membrane: high frequencies at the stiff base and low frequencies at the flexible apex.

Vestibular System

The sensory organ of equilibrium and balance comprising the three semicircular canals, the utricle, and the saccule.

Semicircular Canals

Three perilymph-filled orthogonal bony loops (superior, horizontal, and posterior) that act as accelerometers to sense angular head movements in three dimensions.

Crista Ampullaris

The receptor organ of balance located in the ampullae of the semicircular canals as well as the utricle and saccule, containing hair cells that sense acceleration.

Afferent vs. Efferent Auditory Innervation

Afferent pathways conduct sensory nerve impulses from the cochlear hair cells to the brain, while efferent pathways carry inhibitory signals from the brain to hair cells to suppress background noise and improve signal-to-noise ratio.

Primary Auditory Cortex

The final central destination of the auditory pathway located within the temporal lobe that processes incoming electrochemical auditory signals.

Articulation

The precise adjustments and shaping of the vocal tract produced by moving the articulators.

Articulators

The mobile and immobile anatomical structures of the vocal tract that modify acoustic energy to shape sound into meaningful units of speech.

The Skull

The skeletal framework comprising $22$ bones, categorized into $8$ cranial bones that protect and house the brain and $14$ facial bones that support articulation, chewing, and expression.

Sagittal Suture

The midline cranial seam that joins the two parietal bones, dividing the skull into left and right halves.

Coronal Suture

The suture that divides the frontal bone from the parietal bones, separating front from back.

Lambdoidal Suture

The suture separating the occipital bone from the parietal bones posterior to the cranium.

Occipitomastoid Suture

The suture that separates the occipital bone from the mastoid portion of the temporal bone.

Frontal Bone

An unpaired cranial bone that forms the forehead, the anterior brain case, the roof of the nasal cavity, and contains two frontal sinuses.

Glabella

The smooth bony prominence on the frontal bone situated directly above the nasal notch.

Parietal Bones

Paired cranial bones separated at the midline by the sagittal suture that form the upper sides and roof of the cranium.

Temporal Bone

Paired cranial bones covering the lateral skull below each temple, divided into five portions: tympanic, petrous, squamous, mastoid process, and styloid process.

Occipital Bone

An unpaired cranial bone forming the lower back portion of the cranium; it articulates with C1 and C2 and features the foramen magnum.

Foramen Magnum

The large opening in the base of the occipital bone through which the spinal cord passes.

Ethmoid Bone

An unpaired cranial bone situated behind the frontal bone that separates the nasal cavity from the brain, composed of the cribriform plate, crista galli, ethmoidal labyrinths, and perpendicular plate.

Crista Galli

The upward vertical projection of the ethmoid bone that serves as an attachment point for the falx cerebri of the dura mater.

Cribriform Plate

The perforated horizontal portion of the ethmoid bone that separates the cranial cavity from the nasal space.

Sphenoid Bone

A butterfly-shaped central cranial bone featuring greater and lesser wings that forms part of the eye orbit and portions of the cranial base.

Paranasal Sinuses

Four pairs of air-filled mucosal cavities within the skull (frontal, sphenoid, ethmoid, and maxillary) that slightly reduce skull weight and contribute minimally to acoustic resonance.

Vomer Bone

A single, plow-shaped facial bone that forms the inferior and posterior portion of the bony nasal septum, dividing the nasal cavity into right and left nares.

Nasal Conchae

Three pairs of scroll-shaped facial bones (inferior, middle, and superior) that create four air channels in the nasal cavity to warm, filter, and humidify inspired air.

Zygomatic Bones

Paired facial bones forming the prominent cheekbones and the lateral and inferior margins of the orbital cavities.

Lacrimal Bones

The smallest and most fragile paired facial bones, situated in the anterior medial wall of each orbit and contributing to the nasal cavity.

Mandible

The largest and strongest bone of the face, housing the lower teeth; its condylar process articulates with the temporal bone to form the temporomandibular joint (TMJ).

Maxillae

Paired facial bones forming the upper jaw, housing upper teeth, and fusing at the intermaxillary suture to form the anterior $2/3$ of the hard palate.

Palatine Bones

Paired L-shaped bones located behind the maxillae that form the posterior third of the hard palate and part of the posterior nasal cavity wall.

Orbicularis Oris

The circular muscle complex surrounding the lips that functions as a drawstring to close, cinch, and protrude the lips.

Buccinator Muscle

The primary cheek muscle running from the maxilla, mandible, and pterygomandibular ligament into the lips; it compresses the cheek against the teeth during mastication.

Risorius Muscle

A superficial facial muscle running from the lateral face into the corners of the mouth to retract the lips at the angles.

Zygomaticus Major Muscle

A facial muscle running from the zygomatic arch to the corner of the orbicularis oris that elevates and retracts the angle of the mouth during smiling.

Depressor Anguli Oris

A triangular facial muscle originating on the mandible and inserting into the lower lip at the corner of the mouth to depress the corners downward.

Mentalis Muscle

A facial muscle coursing from the lower mandible into the lower lip that protrudes the lower lip and wrinkles the skin of the chin.

Platysma Muscle

A broad, thin sheet of muscle covering the neck from the pectoralis major and deltoid to the mandible and mouth corners, acting to depress the mandible.

Temporalis Muscle

A large, fan-shaped muscle of mastication originating on the temporal and parietal bones and inserting on the coronoid process and ramus of the mandible to elevate and retract the jaw.

Masseter Muscle

A powerful muscle of mastication originating on the zygomatic arch and inserting onto the coronoid process and ramus of the mandible to elevate and protrude the jaw.

Lateral Pterygoid Muscle

A masticatory muscle running from the sphenoid to the condyle of the mandible and TMJ that causes lateral jaw movement unilaterally and depresses the mandible bilaterally.

Medial Pterygoid Muscle

A muscle of mastication running from the sphenoid and palatine bones to the mandibular ramus that elevates the jaw and aids in side-to-side grinding motions.

Pharyngeal Constrictor Muscles

Three overlapping, fan-shaped muscular layers—superior, middle, and inferior—that sequentially squeeze food downward into the esophagus during swallowing.

Cricopharyngeus Muscle

A muscular ring located at the lowest border of the inferior constrictor connecting the cricoid to the esophagus, forming the pharyngoesophageal (PE) segment that must relax for the bolus to enter the esophagus.

Stylopharyngeus Muscle

A muscle originating from the styloid process of the temporal bone that blends into the pharyngeal constrictors to elevate and dilate the pharynx.

Salpingopharyngeus Muscle

A muscle extending from the cartilaginous Eustachian tube into the palatopharyngeus to elevate the pharyngeal wall during deglutition.

Palatopharyngeus Muscle

A muscle running from the soft palate to the thyroid cartilage that narrows the pharynx and forms the posterior faucial pillar.

Dentition (Adult vs. Deciduous)

The human dental arch comprising $32$ permanent teeth in adults ($4$ central incisors, $4$ lateral incisors, $4$ cuspids, $8$ bicuspids, and $12$ molars) versus $20$ deciduous teeth in children (no bicuspids, only $2$ molars per quadrant, erupting between $6 - 24$ months).

Class I Occlusion

The normal anatomical relationship where upper incisors slightly overlap the lower incisors anteriorly.

Class II Malocclusion (Overbite)

A condition characterized by excessive anterior projection of the upper incisors relative to the lower incisors, which can also be caused by a small mandible (micrognathia).

Class III Malocclusion (Underbite)

A condition characterized by an anteriorly prominent mandible (prognathia) relative to the maxilla.

Hard Palate

The rigid bony roof of the oral cavity and floor of the nasal cavity formed anteriorly by the palatine processes of the maxillae and posteriorly by the horizontal plates of the palatine bones.

Alveolar Ridge

The thickened, raised anterior part of the maxilla and mandible containing tooth sockets, serving as a primary point of articulation for coronal consonants.

Velum (Soft Palate)

A movable muscular valve posterior to the hard palate attached via the palatal aponeurosis that elevates to seal the velopharyngeal port for non-nasal phonemes.